VT100.net Terminals and Printers Handbook 1983-84

Appendix K

Traditional Terminals and Printers

Appendix K provides a reference guide to Digital's printers and printing terminals that have made a major impact in the marketplace but are currently being replaced or have been replaced by new products.

DECprinter IV (LA34)/DECwriter IV (LA38)

The DECprinter/DECwriter IV are 300 baud, 30 characters per second desk-top terminals that can print at burst speeds up to 45 characters per second. The LA34/LA38 is especially useful for applications that require a terminal with forms-handling capabilities. It permanently stores a standard computer printout format, so when the terminal is powered-up it automatically assumes:

The baud rate is set according to the switch settings on the terminal.

However, you can easily change these settings to suit specific application needs. In off-line setup mode, you can choose any of the standard settings right from the keyboard.

You can select variable character sizes of 10, 12, 13.2, and 16.5 characters per inch. If you choose to use 13.2 characters per inch, a full 132 character line will fit on an 11 inch wide piece of paper, while using 16.5 characters per inch, a full 132 character line will fit on an 8.5 inch wide sheet. If a full width form of 37.8 cm (14 7/8 inches) is used, the terminal can print to 174 characters per line at 13.2 char/in, and 216 characters per line at 16.5 char/in.

You can also select from six line spacing settings of 2, 3, 4, 6, 8 or 12 lines per inch. Any form width from 7.6 cm to 37.8 cm (3 to 14.9 in) can be used. Also, you can position left and right margins and horizontal tabs anywhere within that form.

The LA34-RA, LA34-VA and LA34-WA have graphics capabilities. They produce hardcopy graphics and text from printer ports used with the VT125, VT240 or VT241 graphics terminals, as an output device for the GIGI (VK100) terminal, or accept data directly from the CPU.

The basic design of the DECwriter IV contributes to its reliability as well as its maintainability. A single logic board is used, thus reducing the component count and increasing circuit reliability. In sense printhead jams instantly. When a printhead jam occurs, the power is automatically removed from the printhead drive until the jam is corrected and the user restarts the terminal. This action prevents motor overloads and blown fuses. The printhead has been designed and tested to print over 100 million characters and can be adjusted to adapt to various forms thicknesses.

The LA34 and LA38 are easy to maintain. Both are designed to operate reliably without scheduled preventative maintenance; yet if a problem occurs it can be disassembled easily because of its modular design. Printing self-test diagnostics are built into its basic design, allowing quick and accurate identification of any faulty components. Both the LA34 and the LA38 also use snap-in ribbon cartridges.

Whenever possible, the LA34 and LA38 use ANSI standard escape sequences to control their capabilities. These same escape sequences are also implemented on Digital's LA12, LA100, and LA120 hardcopy terminals and the VT100 series of video terminals.

The DECwriter IV and DECprinter IV are being phased out and replaced by the Letterprinter 100, Letterwriter 100 and the DECwriter Correspondent.

DECwriter II (LA36)

The DECwriter II is a 96-character ASCII upper- and lower-case 7 × 7 dot matrix teleprinter. The DECwriter II accepts one to six part forms or standard 132-column line printer paper. It has five vertical adjustments for accurate forms placement. It is capable of 10 characters per inch horizontal spacing and 6 lines per inch vertical spacing.

The DECwriter II includes many practical, functional and operator convenience features. Among these is true 30 characters per second throughput accomplished by a 60 characters per second catchup mode, which is activated any time more than one character is present in the 16-character buffer. The typewriter-style keyboard makes the transition from typewriter to terminal easy. For comfortable use, the LA36 stand is the same height as most typewriter tables.

Other DECwriter II features include paper out sensor, print window, column scale, pointers, 14-key numeric keypad, half- or full-duplex control on operator's console, and last character visibility. For communication purposes, the terminal includes an integrated 20 mA current loop interface with jumpers for active mode and an EIA interface with modem control. Available options include: paper stacking tray, work surfaces, APL/ANSI dual character set, acoustic coupler, EIA interface with timed disconnect, auto answer, and modem control.

The LA36 has been replaced by the Letterwriter 100 (see chapter 10) and the DECwriter III (see chapter 14).

DECprinter I (LA180)

The DECprinter I is a 128-character ASCII upper- and lower-case 7 × 7 dot matrix printer. The DECprinter I accepts one to six part forms or standard 132-column lineprinter paper. It prints at a speed of 180 characters per second.

DECprinter I has many operator features that make it easier to use. Included are a forms-length switch that sets the top-of-form to any of eleven common lengths, a paper-out switch and alarm, and a high-reliability printhead. Also featured are infinitely variable forms adjustment, variable forms width, and multipart forms capability.

Other DECprinter I components include the carriage system, ribbon feed system, and paper feed system. The carriage system transports the head along the horizontal axis of the machine and provides accurate horizontal positioning for character placement and printhead adjustment for clean impressions on a variety of forms. The ribbon feed system is driven by the carriage motion only when the carriage is moving from left to right. This prevents smudging when the DECprinter is not printing. The paper feed system is a stepping-motor-driven tractor feed. The tractor design provides 3-to-4 pin engagement of the form and a flat bed for control and positive feeding of multipart forms. Paper may be fine-positioned vertically by pushing the line feed knob inward and rotating it in the direction desired.

The LA180 has been phased out and the replacement terminal recommended is the DECprinter III or Letterprinter 100.

LP11-C/LP11-D Lineprinters

The LP11-C and LP11-D lineprinters are drum printers designed to handle heavy production loads. They can be used with any UNIBUS PDP-11 or VAX based system.

The LP11-C features a print speed of up to 900 lines per minute using a 64-character set. Both can print on single or multipart forms so you can expand your application capabilities. Also, the LP11-C and LP11-D lineprinters have a 132-column line.

In addition to full line buffering, the LP11-C and the LP11-D are program compatible with other LP11 series lineprinters. Each offers jumper-selectable universal power supply for 120 Vac or 240 Vac operation.

The LP11-C and LP11-D operate by passing paper and inked ribbon between a row of hammers and a continuously-rotating metal drum. The drum surface contains 132 columns of all print characters. Data to be printed is received and stored in a full line buffer. Printing starts when a control character, such as line feed or carriage return, is sent. If more than 132 characters are sent before the control character, the extra characters are disregarded.

Printing is accomplished by scanning the stored characters in synchronization with the rotating drum characters and actuating the appropriate hammer as the desired characters move into the printing position.

The LP11-C/D represents older drum technology. Digital recommends the LP26, LP27, or the LN01 as replacements, depending on your application.